We plan to use the extensive data of the Child Health and Development Studies, covering the prenatal episode as well as the children's health and development until adolescence, to test hypotheses regarding long-term effects of prenatal barbituate exposure. A large body of published studies, mainly based on experiments with rodents, emphasizes changes in behavior of maturing and adult animals as a result of prenatal or perinatal exposure to barbiturates. Few long-term studies on humans have been done, notwithstanding a rather frequent use of barbiturates, also during pregnancy. The data sets of CHDS are particularly well suited for evaluations of long-term effects as our data include completely coded information on pharmaceuticals, linked to the diseases or conditions for which these drugs were prescribed. Developmental examinations of 5 year olds, 10 year olds and adolescents provide information on cognitive development and on behavioral characteristics. This information will be used to evaluate associations between prenatal barbiturate exposure and later behavioral characteristics.